The present invention relates to an arrangement of magnetic recording and/or readout heads for disc memories, these discs comprising on their surfaces a certain number of concentric magnetic areas each constituted by a particular number of circular tracks, the heads being for their part mounted on pads borne by supports so as to be able to move radially with respect to the discs, at a very short distance from the face concerned of the latter.
At present, two different types or arrangement of magnetic heads with respect to a group of magnetic discs are essentially known: those with fixed multiple heads, one head then being provided for each track and on each surface of the disc, which reduces to the maximum the access time to the data on the track concerned, but multiplies very considerably the number of heads of the arrangement; and those with a single but movable head.
The latter type of arrangement is more economical in heads, since one head per surface suffices, but each magnetic head must then be movable radially over the whole extent of the radius of the discs, which, in the majority of cases (head initially distant from the track concerned), increases considerably the access time to the data on the track, this access time t comprising the access time t.sub.1 to the track concerned, plus the access time t.sub.2 to the data sought in this track.
For a given rotary speed of the discs, the element t.sub.2 of this sum cannot be reduced, but it is possible to seek to reduce the time t.sub.1 of access to the tracks.